Chacarilla Formation
geologic formation in Chile
The Chacarilla Formation (Spanish: Formación Chacarilla) is an Oxfordian to Early Cretaceous geologic formation of the Tarapacá Basin in northern Chile, close to the border with Bolivia. The marine and fluvial formation preserves several dinosaur trackways and has been declared a Natural Sanctuary (Spanish: Santuario de la Naturaleza) in 2004.
Description
The formation comprises a sequence of rhythmically alternating shales and red sandstones with a minimum thickness of 1,100 metres (3,600 ft). The lower part of the formation was deposited under marine conditions and the upper part in a meandering river floodplain and point bar environment. Paleocurrent analysis demonstrated a flow direction towards the west, northwest and west-northwest.
The formation contains ichnofossils of theropods and ornithopods, occurring in the Early Cretaceous upper part of the formation, which is marked by an angular unconformity, overlain by volcanic and clastic rocks of the Late Cretaceous to Early Paleocene Cerro Empexa Formation. The top of the formation is not younger than Aptian.
Fossil content
Fossil stegosaur, sauropod and theropod tracks and fossil flora have been reported from the formation.
The fourteen trackways of the Chacarilla III tracksite consist of 76 individual footprints. Two of the trackways consist of large ornithopod footprints (average footprint length 39 centimetres (15 in) and average width 32 centimetres (13 in)).
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This entry incorporates text from “Chacarilla Formation” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.